--- title: Get started slug: experimentation-strategy/data-docs/BQy3-get-started docTags: createdAt: 2026-07-22T21:06:33.453Z --- For a complete description of the Event API, see the [Event API reference](docId\:LHIwyTMwVE6kNISdESDTw). ## Create an experiment Reuse an existing experiment, or create a new experiment in the Optimizely [application](https://app.optimizely.com/v2/) and add at least one event and metric. Start the experiment before proceeding to the next step. For information on how to create an experiment, see the following documentation: **Optimizely Web Experimentation and Optimizely Performance Edge experiments** - [Steps to create an experiment in Optimizely Web Experimentation or Performance Edge](docId\:KiJTfQQjUsHKpV4igZ7Ea) - [Create an experiment in Optimizely Performance Edge](docId\:dtqjtN-Kjo-ycd7czJMPY) (developer guide) - [Configure events in Optimizely Experimentation](docId\:gq5wzoPd77xOJwNSfxqm8) - [Create a metric in Optimizely Experimentation](docId\:cphstZe3xKhsY7WsnnLZK) **Optimizely Feature Experimentation experiments** - [Quickstarts](docId\:Z5naN7OMaPJkz-UBny_ll) - [Run A/B tests](docId:8pnfCv-sR37goLcxTtCPv) - [Choose metrics](docId\:e2qGf29S6pO8SW90_IVuH) - [Create events](docId\:v2goO-UxyIA4AtTSR-h-9) ## Collect the required identifiers The following table shows the required fields for the JSON object described in the [Build the JSON data object](docId\:BQy35J-2Rou_0kPcXKtqq) section. To locate these fields, follow the instructions in [Find IDs for API calls](docId\:uu6zmA5Bkeqsq84hqUmL3). | Field | Type | Required to activate a user | Required to track event | | ------------------ | ----------------------- | --------------------------- | ----------------------- | | **account\_id** | Account identifier | Yes | Yes | | **visitor\_id** | Visitor identifier | Yes | Yes | | **timestamp** | Event timestamp | Yes | Yes | | **entity\_id** | Event entity identifier | Yes | Yes | | **campaign\_id** | Campaign assignment | Yes | No | | **experiment\_id** | Experiment assignment | Yes | No | | **variation\_id** | Variation assignment | Yes | No | ## Build the JSON data object The JSON data object structure differs depending on whether you are activating a user or tracking a conversion event. :::hint{type="danger"} A single JSON object must be **3.5 MB** or less. ::: ### Activate users To activate a user to a variation, send a JSON object that includes: - The `decisions` array, containing the `campaign_id`, `experiment_id`, and `variation_id`. - The `events` array, containing a special event of type `campaign_activated`, which represents the visitor being assigned to a particular variation. By convention, this event's `entity_id` is mapped to the corresponding variation's `campaign_id` as given in the `decisions` array. - The `enrich_decisions` field set to `true` to enable Optimizely's Experimentation Events Export feature. For information about this field, see the [Event API reference](docId\:LHIwyTMwVE6kNISdESDTw). Also, see [How Optimizely Experimentation counts conversions](docId\:onBazDzYYz526tL9aQF0s). :::hint{type="info"} * The `campaign_activated` event must have a `timestamp` equal to or earlier than other tracked conversion events, as explained in [How Optimizely Experimentation counts conversions](docId\:onBazDzYYz526tL9aQF0s). Any conversion events with timestamps older than the related decision event will not be counted on the [results page](docId\:mrUblIuNVOZc1dvjWdsbw). * A single visitor can only be exposed to one variation of one experiment within a campaign. Ensure that each `campaign_activated` event for a given visitor is mapped to only one `campaign_id`, `experiment_id`, and `variation_id` triplet. * You do not need to activate a user if they have already been activated by a Feature Experimentation or Web Experimentation `activate()` call. ::: The example includes the optional `client_name` and `client_version` fields. Include these fields for debugging. ```json { "account_id": "1887578053", "visitors": [ { "visitor_id": "test_user", "snapshots": [ { "decisions": [ { "campaign_id": "9560823711", "experiment_id": "5733750339", "variation_id": "6630810318" } ], "events": [ { "entity_id": "9560823711", "type": "campaign_activated", "timestamp": 1491519130343, "revenue": 9900, "uuid": "12a25c92-7edd1-1c30-21a8-aa4c850671e4" } ] } ] } ], "anonymize_ip": true, "client_name": "Optimizely/event-api-demo", "client_version": "1.0.0", "enrich_decisions": true } ``` ### Track conversion events A [conversion event](https://www.optimizely.com/optimization-glossary/conversion/) represents a visitor taking a specific action on your site. When `enrich_decisions` is true, Optimizely retains the activation information for each visitor (`campaign_id`, `experiment_id`, and `variation_id`) and automatically matches subsequent conversion events to the correct variation. See the [Activate users](docId\:BQy35J-2Rou_0kPcXKtqq) section for information about the `client_name`, `client_version`, and `enrich_decisions` fields in the following code example. Include attributes for conversion events. Adding attributes lets you [segment your results](docId\:mrUblIuNVOZc1dvjWdsbw) properly. :::hint{type="info"} - You still need to pass an empty `decisions` array, as shown in the following example. - The conversion event must have a timestamp equal to or more recent than the timestamp of the `campaign_activated` event, as explained in [How Optimizely Experimentation counts conversions](docId\:onBazDzYYz526tL9aQF0s). Any conversion events with timestamps older than the related `campaign_activated` event will not be counted on the Results page. - Within a session, events of the same UUID are deduplicated. It is not sufficient to have only a unique `entity_id`. Each event needs a UUID to avoid deduplication. ::: ```json { "account_id": "your_account_id", "visitors": [ { "visitor_id": "test_user", "attributes": [], "snapshots": [ { "decisions": [], "events": [ { "entity_id": "1260528912", "key": "test_event", "timestamp": 1540996187279, "uuid": "12a25c92-7edd1-1c30-21a8-aa4c850671e4", "revenue": 10000 } ] } ] } ], "anonymize_ip": true, "client_name": "Optimizely/event-api-demo", "client_version": "1.0.0", "enrich_decisions": true } ``` See the [Event API reference](docId\:LHIwyTMwVE6kNISdESDTw) for required and optional fields. ## Send data object as `POST` call After you build the JSON data object, send it to the following Event API endpoint as a `POST` call: ``. The API does not require an authorization token. The following is a sample cURL request. After the API receives your request, it queues the JSON payload for processing and returns a `204` status code. :::hint{type="warning"} The response does not indicate that your JSON has been validated. Consult [the Event API reference](docId\:LHIwyTMwVE6kNISdESDTw) for more guidance. ::: ```http curl -X POST -H "Content-Type: application/json" -d "https://logx.optimizely.com/v1/events" { "account_id": "your_account_id", "visitors": [ { "visitor_id": "test_user", "attributes": [], "snapshots": [ { "decisions": [], "events": [ { "entity_id": "1260528912", "key": "test_event", "timestamp": 1540996187279, "revenue": 10000, "uuid": "12a25c92-7edd1-1c30-21a8-aa4c850671e4" } ] } ] } ], "anonymize_ip": true, "client_name": "Optimizely/event-api-demo", "client_version": "1.0.0", "enrich_decisions": true } ``` :::hint{type="info"} See the [Activate users](docId\:BQy35J-2Rou_0kPcXKtqq) section for information about the `client_name`, `client_version`, and `enrich_decisions` fields shown in the preceding code sample. ::: ## Verify results Results typically display on the [Experiment Results page](docId\:mrUblIuNVOZc1dvjWdsbw) within a few minutes. To debug common issues, see [Troubleshoot the Event API](docId\:twQQ18TqlkQ-PamsvWifE).